1. Field of the Invention
The present invention relates to a selecting device for orienting in a predetermined position a succession of caps for sealed pourable food product packages.
2. Description of the Related Art
Many pourable food products, such as fruit juice, UHT (ultra-high-temperature treated) milk, wine, tomato sauce, etc., are sold in packages made of sterilized packaging material.
A typical example of such a package is the parallelepipedal package for liquid or pourable food products known as Tetra Brik Aseptic (registered trademark), which is formed by folding and sealing laminated strip packaging material. The packaging material has a multilayer structure comprising a layer of fibrous material, e.g. paper, covered on both sides with layers of heat-seal plastic material, e.g. polyethylene. In the case of aseptic packages for long-storage products such as UHT milk, the packaging material comprises a layer of barrier material, e.g. an aluminium film, which is superimposed on a layer of heat-seal plastic material and in turn covered with another layer of heat-seal plastic material defining the inner face of the package eventually contacting the food product.
As is known, packages of the above type are produced on fully automatic packaging machines, on which a continuous tube is formed from the packaging material supplied in strip form. The strip of packaging material is sterilized on the packaging machine, e.g. by applying a chemical sterilizing agent, such as a hydrogen peroxide solution; following sterilization, the sterilizing agent is removed, e.g. vaporized by heating, from the surfaces of the packaging material; and the strip of packaging material so sterilized is kept in a closed sterile environment, and is folded and sealed longitudinally to form a vertical tube.
The tube is filled with the sterilized or sterile-processed food product, and is sealed at equally spaced cross sections at which it is then cut into pillow packs, which are subsequently folded mechanically into finished, e.g. substantially parallelepipedal packages. Various pasteurized pourable food products, such as milk and fruit juice, are packaged as described above--but with no need to sterilize the packaging material--in packages known as Tetra Brik (registered trademark) or in other types such as so-called Tetra Rex (registered trademark) packages.
Some packages formed as described above are known to comprise an opening through which to pour out the food product; and a cap applied to the packaging material to close the opening.
The caps are normally housed in bulk inside a store, from which they are fed successively to a selecting device in two opposite input positions, one upside-down with respect to the other.
The selecting device substantially comprises a conveyor--e.g. defined by an inclined guide member--for feeding the caps to an output station; a sensor assembly for determining whether the caps fed past it are set to a predetermined output position corresponding with one of the input positions; and an expulsion member, e.g. an air nozzle, which is activated selectively by the sensor assembly to feed the caps in said output position to a fitting device for fitting the caps to the packaging material. In particular, in the case of aseptic food product packaging, the caps are fitted directly to the finished packages; otherwise, the caps are fitted to the strip packaging material prior to folding the material into a vertical tube.
Conversely, if the cap fed past the sensor assembly is set to other than the output position, the expulsion member is not activated and the cap is fed back to the store from which it is again fed to the selecting device.
The number of caps fed past the sensor assembly in other than the output position, and hence fed back to the store, is normally fairly high, thus resulting in poor transportation efficiency and in only 70% of the capacity of the selecting device being exploited.